Factors influencing the discharge mode for microsecond-pulse gliding discharges at atmospheric pressure

This work presents experimental results on different discharge modes for microsecond-pulse gliding discharges and their transition, and then analyzes the effect of the gap distance and flow rate on the discharge modes. The current amplitude, energy consumption per pulse and voltage range are used to reflect some discharge characteristics of discharge modes. The results show that there are three discharge modes for microsecond-pulse gliding discharges, i.e. the corona, diffuse and spark. Among the three modes, the values of the amplitude of the discharge current and the energy consumption per pulse for corona mode are lowest, then the diffuse mode and spark mode accordingly. When the gap spacing is smaller than 5 mm, there is no diffuse mode, and the corona discharges directly transit to spark discharges with the increase of the voltage. When the gap spacing is or more than 5 mm, the corona-diffuse-spark mode transition with the increase of the voltage is observed. The voltage range for diffuse discharge increases with the gap spacing. Moreover, when the flow rate increases, the ignition voltage for spark discharges increases, but the ignition voltage for diffuse discharges slightly changes, resulting in the voltage range for diffuse discharges increases. Therefore, diffuse mode is more likely to be obtained in a large gap with a relatively high flow rate.